Synthesis and Characterization of a New Class of μ₃-OH-Bridged Trimers That Contain Octahedrally Coordinated Divalent Metal Ions Bridged by Three Acetate Ligands and a Unique Catecholate Ligand. Solid State Molecular Structures of the [(py)₅MII₃(OAc)₃(μ₃-OH)((cat)] Complexes (M = Mn(II), Fe(II), Co(II), Ni(II))

The synthesis and structural characterization of a new class of “basic” trinuclear acetate clusters with solely divalent metal ions and a central μ3-OH ligand are reported. These molecules with the [(py)5MII3(OAc)3(μ3-OH)(cat)] stoichiometry (M = Mn, Fe, Co, Ni) are X-ray isomorphous and isostructural and contain octahedrally coordinated metal ions. The core consists of an antiferromagnetically coupled M3 unit with the metals arranged in the corners of an isosceles triangle. Two of the M−M distances vary between 2.98 and 3.16 Å, and the longer M−M distance is observed between 3.65 and 3.76 Å. As expected from the relative ionic radius lengths, these distances increase gradually from Ni(II) to Mn(II).